Calculate the Greatest Common Factor or GCF of 12, 20, 70 and 98
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The instructions to find the GCF of 12, 20, 70 and 98 are the next:
1. Decompose all numbers into prime factors
| 12 | 2 |
| 6 | 2 |
| 3 | 3 |
| 1 |
| 20 | 2 |
| 10 | 2 |
| 5 | 5 |
| 1 |
| 70 | 2 |
| 35 | 5 |
| 7 | 7 |
| 1 |
| 98 | 2 |
| 49 | 7 |
| 7 | 7 |
| 1 |
2. Write all numbers as the product of its prime factors
| Prime factors of 12 | = | 22 . 3 |
| Prime factors of 20 | = | 22 . 5 |
| Prime factors of 70 | = | 2 . 5 . 7 |
| Prime factors of 98 | = | 2 . 72 |
3. Choose the common prime factors with the lowest exponent
Common prime factors: 2
Common prime factors with the lowest exponent: 21
4. Calculate the Greatest Common Factor or GCF
Remember, to find the GCF of several numbers you must multiply the common prime factors with the lowest exponent.
GCF = 21 = 2
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